Nonlinear Characteristics of Electrocardiograph Signals Based on Fractal

基于分形的心电信号非线性特征研究

School of Mechanical Engineering, Northwestern Polytechnical University, Xi'an 710072, China

Received: 12 March 2017

Abstract

In view of the nonlinear properties of Electrocardiograph (ECG) signal, the application of fractal methods from nonlinear system theory for the analysis of ECG signals has gained increasing interest.In this study, analysis of the objects are ECG signals of four sinus rhythms. Some important phenomena and conclusions have been captured and drawn after analyzing with and plotting the graphics of multi-fractal spectrum and auto-correlation functions. Additionally, the Hurst(H) parameters illustrate that self-similarity is a common property of the ECG signals, but the smaller H of the normal sinus rhythm(NSR) cause the obvious randomness of NSR. The further research of multi-fractal spectrum shows that the ECG signals all present local singular characteristics, but there are inconsistencies in the same type of sinus rhythm ECG signal. While, the inconsistency led to obvious classification, especially in NSR. As the conclusion, the results can be used as an effective complementary method for non-invasive diagnosis and early warning of heart disease.

摘要

采用分形理论分析心电信号的非线性特征。以几种常见窦性心率的心电信号为分析对象，通过分析其单重分形和多重分形谱特征，绘制自相关函数图和多重分形谱图，研究不同窦性心律的非线性特征，得出结论性结果。研究结果表明：这4种心电信号均具有自相关特性，其中正常窦性心律的自相关函数衰减迅速并且Hurst参数较小，表现出明显的随机特征。多重分形谱的进一步研究表明，各类心电信号同时存在局部奇异特性，同类型窦性心律心电信号的多重分形谱出现特征的不一致性和分类现象，其中正常窦性心律的分类较为明显。这一研究结果，可作为一个有效的补充方法，用于心脏疾病的无创诊断及预警。